32 Part I • Information Technology
department up to enterprise-wide systems that have
assumed many of the roles of mainframe computers.
It can be useful to divide today’s midrange systems
into two categories. At the low-end come machines that are
essentially high-powered PCs, typically built around Intel
Xeon processors or AMD Opteron processors and often
using Windows Server as the server operating system. It is
also possible to run the UNIX or Linux operating system
on these Intel- or AMD-based servers, but this is not as
common.^3 The major players in this market category are
Hewlett-Packard, Dell, IBM, and Fujitsu (Japan).
At the high-end are machines that are powered either
by RISC processors developed by the vendor (such as IBM
or Sun Microsystems) or by top-of-the-line Intel or AMD
microprocessors (such as the Intel Itanium). For the most
part, these high-end machines run either the Linux operat-
ing system or some variation of the UNIX operating sys-
tem. In this market subsegment, the leaders are IBM,
Hewlett-Packard, and Sun Microsystems.
As an example, IBM’s entry in this UNIX/Linux
market category is IBM Power Systems (formerly called
System p, and before that RS/6000), employing IBM-
developed RISC chips. Among the many models of the
Power server are the Power 520 Express with up to
4 processors and the top-of-the-line Power 595 server
with up to 64 processors. The Power 520 Express can
have a memory capacity of up to 64 gigabytes (billion
bytes), and the Power 595 can have a memory capacity of
up to 4 terabytes (trillion bytes). The Power 520 Express
has a starting price under $6,000, while the Power 595 can
run into hundreds of thousands of dollars. IBM Power
servers are powered by IBM’s POWER6 64-bit micro-
processor^4 chip, which was the world’s fastest processor
chip when it was introduced in 2007. The POWER6 chip,
which contains 790 million transistors, is a dual-core
processor (two processors on one chip). We should note
that the multiple processors on a Power server can operate
as a symmetric multiprocessor (SMP),which means
that all the processors are identical, with each processor
operating independently of the others. Thus each proces-
sor can simultaneously be running a separate application.
While the Power server primarily runs either Linux or
IBM’s flavor of UNIX, it can also run the IBM i operating
system. This is important because it will permit users of
IBM’s System i machines (formerly the AS/400), which
are being merged into Power Systems, to migrate all their
applications to Power servers. Power Systems and its
predecessor RS/6000 series and AS/400 series have been
a tremendous success for IBM, with well over a million
systems shipped to commercial and technical customers
throughout the world (IBM Web site, 2007, 2008, and
2009b; Niccolai, 2009).(^3) Operating systems are considered later in this chapter. UNIX and Linux
are both “open” operating systems that are used on many midrange sys-
tems, supercomputers, and now mainframes.
(^4) This means that the processor chip is capable of handling 64 bits of data
at a time, whereas many microprocessor chips handle only 32 bits of data
at a time.
Blade Servers
In the 2000s, the blade serverbecame a popular way to handle multiple servers in a computing center.
This is an idea that makes eminent sense—multiple server modules, called blade servers or just blades,
are housed in a single chassis, saving space in the computer center, reducing the required cabling, and
improving system management. The older options are to have each server module in a tower, much like
an under-desk PC, or to mount them in an open rack, with all the connections leading from the rack.
The blade server chassis provides the power supply for the blades, the management system, and the
network switch; each blade has its own processor, memory, and hard drive. Diskless blades are also pos-
sible in larger blade servers, where the disk storage is external to the blades and shared among them.
As an illustration, let’s consider IBM’s BladeCenter H chassis, which is less than 16 inches tall and
offers up to 14 bays, each of which can hold a two-processor blade. The blade servers are 30 millime-
ters wide (about 1.2 inches) and are mounted vertically in the chassis—much like sliding a book into a
bookshelf. The blade server slides into a bay and plugs into the chassis, sharing power, fans, switches,
and ports with the other blade servers in the chassis. Interestingly, you can mix and match types of blade
servers and the operating systems they use in a single chassis: BladeCenter permits the use of Intel Xeon
blades, AMD Opteron blades, or IBM POWER6 blades in the same chassis. Hewlett-Packard is the mar-
ket leader in blade servers, with significant competition from IBM and Dell.
[Based on Patrizio, 2009; and IBM Web site, 2010a]